In 2000, five years after the events of the Outer Heaven Uprising, the American special forces squad Black Chamber, a replacement for FOXHOUND regarding black ops missions, had undergone a secret mission to quell a terrorist takeover in South America that resulted in a Metal Gear being hijacked. After the success fo their mission, they returned to America, only to be caught in an ambush by FOXHOUND, at the time led by Roy Campbell, which left only four known survivors: Marionette Owl, Pyro Bison, Slasher Hawk, and the group commander, Black Arts Viper. They subsequently swore revenge.